dhclient.leases(5) on FreeBSD
The text 1111d28f40de, as FreeBSD 4.5-RELEASE, FreeBSD 4.4-RELEASE, FreeBSD 4.3-RELEASE, FreeBSD 4.2-RELEASE, FreeBSD 4.1.1-RELEASE, FreeBSD 4.1-RELEASE, FreeBSD 4.0-RELEASE, FreeBSD 3.5.1-RELEASE, FreeBSD 3.5-RELEASE, FreeBSD 3.4-RELEASE, FreeBSD 3.3-RELEASE, FreeBSD 3.2-RELEASE shipped it.
DHCP client lease database